During conventional fabrication of textile feedstock, especially of cotton pressed in bales, numerous health, technical and economic problems often arise.
These problems include the development of health threatening molds, especially aflatoxines in the leaves (bracts); insufficient moisture for subsequent treatment steps; and wild behavior of the delivered material in the processing machine or gin before subsequent treatment depending on the quality of the cotton gin, its previous storage condition, press condition and moisture content.
Attempts to pretreat the feedstock to address the problems have been unsuccessful for technical and/or economic reasons.
It is therefore a purpose of the present invention to provide a process to solve health and technical problems which have affected prior art textile feedstock fabrication processes.
It is a further purpose of the invention to provide a process which allows an improvement in the quality of the spun yarn, with a raised yield.
Yet a further purpose of the present invention is to provide a feedstock preparation method which is reproducible, efficient, and which produces a feedstock which is greatly restricted in its biological activity, especially insuring that only a minimal further development of mold fungi can occur, even in the case of a new contamination occurring by means of airborne spores.
The foregoing and other objects of the invention are achieved by a heat treatment of the feedstock in a pressed state, i.e. in the bale. By a specific, gradual heat treatment of the bale at least partial sterilization and a conditioning of the feedstock is effected simultaneously.
The heat treatment of the present invention comprises placing the feedstock in a treatment chamber and subjecting the feedstock to a plurality of treatment cycles comprising the evacuation of the chamber to a reduced pressure, and the application of steam to the feedstock for a treatment period to allow the steam to penetrate into the interior of the bale. At least 4, and preferably 5 treatment cycles are conducted.
The heat treatment can be accomplished by a type of fractional conditioning (alternating evacuation and steaming with holding times) which may be carried out by conventional treating systems as marketed by Xorella AG, CH-5430 Wettingen, Switzerland under the trademark SYSTEM CONTEXOR.
It has been surprisingly found that the present invention makes it possible to successfully treat a heavily pressed cotton bale in an economically reasonable time with an economically justifiable expenditure of energy. The treatment installation is preferably operated according to WO 98/21390 and U.S. Pat. No. 6,094,840.
It has been found that a 5 cycle steaming procedure yields an ultimate temperature of about 80xc2x0 C. in the inner part of the bale. Higher bale temperatures may be desired or utilized when required for sterilization or destruction of biologically active material.